---
id: llm-evaluation-promptfoo-test-cases-and-assertions
title: 'LLM Evaluation Promptfoo Test Cases and Assertions'
schema_type: TechArticle
category: ai
language: en
confidence: medium
last_verified: '2026-06-03'
created_date: '2026-06-03'
generation_method: ai_structured
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
atomic_facts:
  - id: fact-ai-llm-evaluation-promptfoo-test-cases-and-assertions-1
    statement: >-
      Promptfoo documentation describes its configuration guide as covering
      prompts, providers, test cases, assertions, and advanced features.
    source_title: Promptfoo Configuration Guide
    source_url: https://www.promptfoo.dev/docs/configuration/guide/
    confidence: medium
  - id: fact-ai-llm-evaluation-promptfoo-test-cases-and-assertions-2
    statement: >-
      Promptfoo configuration examples define tests with vars for prompt inputs.
    source_title: Promptfoo Configuration Guide
    source_url: https://www.promptfoo.dev/docs/configuration/guide/
    confidence: medium
  - id: fact-ai-llm-evaluation-promptfoo-test-cases-and-assertions-3
    statement: >-
      Promptfoo expected-output documentation describes assertions and metrics
      as LLM output validation.
    source_title: Promptfoo Expected Outputs Documentation
    source_url: https://www.promptfoo.dev/docs/configuration/expected-outputs/
    confidence: medium
completeness: 0.82
known_gaps:
  - Promptfoo evaluation behavior depends on provider settings, model nondeterminism, prompt templates, assertion type, thresholds, test data provenance, retries, caching, and CI gating policy.
disputed_statements: []
primary_sources:
  - title: Promptfoo Configuration Guide
    type: documentation
    year: 2026
    url: https://www.promptfoo.dev/docs/configuration/guide/
    institution: Promptfoo
  - title: Promptfoo Expected Outputs Documentation
    type: documentation
    year: 2026
    url: https://www.promptfoo.dev/docs/configuration/expected-outputs/
    institution: Promptfoo
secondary_sources: []
updated: '2026-06-03'
ai_models:
  - gpt-5-codex
---

## TL;DR

Promptfoo test cases and assertions give agents a concrete way to inspect LLM evaluation inputs, expected behavior, and pass/fail criteria.

## Core Explanation

LLM evaluation needs more than a prompt and a score. Agents should look for the prompt template, provider configuration, test variables, expected outputs, assertion type, threshold, fixtures, and whether the result is used as a CI gate. This helps distinguish model regression from a changed prompt, changed provider, or brittle test data.

Assertion-based evaluation is especially useful for developer workflows because it turns qualitative behavior into repeatable checks. The tradeoff is coverage: assertions must be reviewed against real failure modes and supplemented with human review or statistical sampling when the task is subjective.

## Source-Mapped Facts

- Promptfoo documentation describes its configuration guide as covering prompts, providers, test cases, assertions, and advanced features. ([source](https://www.promptfoo.dev/docs/configuration/guide/))
- Promptfoo configuration examples define tests with vars for prompt inputs. ([source](https://www.promptfoo.dev/docs/configuration/guide/))
- Promptfoo expected-output documentation describes assertions and metrics as LLM output validation. ([source](https://www.promptfoo.dev/docs/configuration/expected-outputs/))

## Further Reading

- [Promptfoo Configuration Guide](https://www.promptfoo.dev/docs/configuration/guide/)
- [Promptfoo Expected Outputs Documentation](https://www.promptfoo.dev/docs/configuration/expected-outputs/)